Systems and methods for securing network paths

ABSTRACT

In one embodiment, a method includes determining a secure path through a first plurality of network nodes within a network and determining an alternate secure path through a second plurality of network nodes within the network. The method also includes routing network traffic through the first plurality of network nodes of the secure path and detecting a failure in the secure path using single-hop BFD authentication. The method further includes rerouting the network traffic through the second plurality of network nodes of the alternate secure path.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Application No.62/829,591 filed Apr. 4, 2019, by Clarence Filsfils, and entitled“Applying attestation tokens to Path Computation Element Protocol (PCEP)and PCE discovery functionalities,” which is incorporated herein byreference as if reproduced in its entirety.

TECHNICAL FIELD

This disclosure generally relates to network paths, and morespecifically to systems and methods for securing network paths.

BACKGROUND

Sensitive information may be transmitted through one or more nodeswithin a network. Certain nodes within the network may becomecompromised. For example, an attacker may gain access to one or more ofthe network nodes. If a network node is compromised, traditionalprotections may prove ineffectual in protecting the sensitiveinformation traversing the compromised node.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example system for securing network paths;

FIG. 2 illustrates another example system for securing network paths;

FIG. 3 illustrates an example method for calculating secure networkpaths;

FIG. 4 illustrates an example method for detecting failures in securenetwork paths; and

FIG. 5 illustrates an example computer system that may be used by thesystems and methods described herein.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Overview

According to an embodiment, an apparatus includes one or more processorsand one or more computer-readable non-transitory storage media coupledto the one or more processors. The one or more computer-readablenon-transitory storage media include instructions that, when executed bythe one or more processors, cause the apparatus to perform operationsincluding determining a secure path through a first plurality of networknodes within a network and determining an alternate secure path througha second plurality of network nodes within the network. The operationsfurther include routing network traffic through the first plurality ofnetwork nodes of the secure path and detecting a failure in the securepath using single-hop Bidirectional Forwarding Detection (BFD)authentication. The operations further include rerouting the networktraffic through the second plurality of network nodes of the alternatesecure path.

In certain embodiments, the apparatus is a local device. Determining thesecure path through the first plurality of network nodes within thenetwork may include calculating, by the local device, the secure pathusing constrained shortest path first (CSPF). The CSPF may use a set ofconstraints to calculate the secure path through the first plurality ofnetwork nodes within the network. A constraint of the set of constraintsmay be associated with a determination that each node of the firstplurality of network nodes of the secure path is trustworthy. In someembodiments, determining the secure path through the first plurality ofnetwork nodes within the network may include receiving the secure pathfrom a path computation element (PCE).

In certain embodiments, the operations may include validating the securepath through the first plurality of network nodes within the network.Validating the secure path may include one of the following: receiving avalidation of the secure path from a controller of the network,receiving a validation of the secure path from a PCE of the network, ordetermining that the secure path is valid based on contents receivedfrom a Record Route Object (RRO) of an Resource Reservation Protocol(RSVP) message. Detecting the failure in the secure path usingsingle-hop BFD authentication may include determining that a PlatformConfiguration Register (PCR) value included in a BFD packet has changed.Detecting the failure in the secure path using single-hop BFDauthentication may include determining that a PCR value included in aBFD packet is different than the expected PCR value. In certainembodiments, the operations may include communicating a path computationrequest (PCReq) message to a PCE to request a secure path to the PCE.

According to another embodiment, a method includes determining a securepath through a first plurality of network nodes within a network anddetermining an alternate secure path through a second plurality ofnetwork nodes within the network. The method also includes routingnetwork traffic through the first plurality of network nodes of thesecure path and detecting a failure in the secure path using single-hopBFD authentication. The method further includes rerouting the networktraffic through the second plurality of network nodes of the alternatesecure path.

According to yet another embodiment, one or more computer-readablenon-transitory storage media embody instructions that, when executed bya processor, cause the processor to perform operations includingdetermining a secure path through a first plurality of network nodeswithin a network and determining an alternate secure path through asecond plurality of network nodes within the network. The operationsalso include routing network traffic through the first plurality ofnetwork nodes of the secure path and detecting a failure in the securepath using single-hop BFD authentication. The operations further includererouting the network traffic through the second plurality of networknodes of the alternate secure path.

Technical advantages of certain embodiments of this disclosure mayinclude one or more of the following. The systems and methods describedherein allow a network node to calculate a secure path to a target host.In certain embodiments, the network node may detect failures in thesecure path after the network node has routed traffic through the securepath. For example, the network node may detect when a node along thesecure path has transitioned from being a secure network node to beingan insecure network node. The network node may use BFD authentication todetect failures in the secure path faster than traditional methods.

Other technical advantages will be readily apparent to one skilled inthe art from the following figures, descriptions, and claims. Moreover,while specific advantages have been enumerated above, variousembodiments may include all, some, or none of the enumerated advantages.

Example Embodiments

In certain embodiments of this disclosure, a node of a networkdetermines secure paths to route traffic through the network. The securepaths may be determined locally using CSPF or remotely using PCEP.Failures in the secure path are detected using BFD. For example, thenetwork node may determine that a node along the secure path has changedfrom being a secure node to being an insecure node by detecting a changein a PCR value included in a BFD packet. Upon detection of the failure,the network node may reroute the network traffic along an alternatesecure path. FIGS. 1 and 2 of this disclosure show example systems forsecuring network paths. FIG. 3 shows an example method for calculatingsecure network paths, and FIG. 4 shows an example method for determiningfailures in secure network paths. FIG. 5 shows an example computersystem that may be used by the systems and methods of FIGS. 1 through 4.

FIG. 1 illustrates an example system 100 for securing network paths.System 100 may be used to calculate secure network paths and/or todetect failures in secure network paths. System 100 or portions thereofmay be associated with an entity, which may include any entity, such asa business or company (e.g., a service provider) that calculates securenetwork paths and/or detects failures in network paths. The componentsof system 100 may include any suitable combination of hardware,firmware, and software. For example, the components of system 100 mayuse one or more elements of the computer system of FIG. 5 .

System 100 includes a network 110, network nodes 120, a controller 130,and a PCE 140. Network 110 of system 100 is any type of network thatfacilitates communication between components of system 100. Network 110may connect one or more components of system 100. This disclosurecontemplates any suitable network. One or more portions of network 110may include an ad-hoc network, an intranet, an extranet, a VPN, a localarea network (LAN), a wireless LAN (WLAN), a wide area network (WAN), awireless WAN (WWAN), a metropolitan area network (MAN), a portion of theInternet, a portion of the Public Switched Telephone Network (PSTN), acellular telephone network, a combination of two or more of these, orother suitable types of networks. Network 110 may include one or morenetworks. Network 110 may be any communications network, such as aprivate network, a public network, a connection through Internet, amobile network, a WI-FI network, etc. One or more components of system100 may communicate over network 110. Network 110 may include a corenetwork (e.g., the Internet), an access network of a service provider,an Internet service provider (ISP) network, and the like. In certainembodiments, one or more portions of network 110 may utilizeMultiprotocol Label Switching (MPLS).

Nodes 120 of system 100 are connection points within network 110 thatreceive, create, store and/or send data along a path. Nodes 120 mayinclude one or more endpoints and/or one or more redistribution pointsthat recognize, process, and forward data to other nodes 120. Nodes 120may include virtual and/or physical network nodes. In certainembodiments, one or more nodes 120 include data communications equipmentsuch as switches, bridges, modems, hubs, and the like. In someembodiments, one or more nodes 120 include data terminal equipment suchas routers, servers, printers, workstations, and the like. One or morenodes 120 may be host computers, ingress nodes, destination nodes, PathComputation Client (PCC) nodes, and the like.

One or more nodes 120 within network 110 may receive incoming traffic.The incoming traffic may include data communications and network trafficoriginating from networks external to network 110. The incoming trafficmay be destined for a target host/IP address within network 110. One ormore nodes 120 may receive a request to route the incoming trafficthrough a secure path within network 110. One or more nodes 120 maydetermine (e.g., calculate) the secure path locally or remotely.

In certain embodiments, one or more nodes 120 (e.g., an ingress node) ofnetwork 110 calculates the secure path locally. One or more nodes 120may calculate the secure path locally using shortest path. In someembodiments, one or more nodes 120 calculate the secure path locallyusing CSPF. CSPF is an extension of shortest path algorithms. The securepath computed by one or more nodes 120 using CSPF may be the shortestpath that fulfills a set of constraints. The constraints may include oneor more of the following traditional constraints: minimum bandwidthrequired per link, end-to-end delay, maximum number of links traversed,include/exclude nodes, Shared Risk Link Groups (SRLG), and the like.This disclosure includes an additional security constraint that is usedby CSPF to calculate the secure path. The security constraint ensuresthat all nodes 120 in the calculated secure path are determined to besecure (i.e., trustworthy). One or more nodes 120 may use information inthe topology of network 110 to determine the secure path. For example,certain nodes 120 may be tagged as secure or insecure, and one or morenodes 120 may calculate the secure path using only nodes 120 that havebeen tagged as secure.

In certain embodiments, one or more nodes of network 110 determine thesecure path remotely. One or more nodes 120 may determine the securepath remotely using information received from PCE 140. In someembodiments, one or more nodes 120 may be PCC nodes that requestcomputations from PCE 140. A PCC node may use PCEP to communicate withPCE 140. For example, the PCC node may send a PCReq message to PCE 140to request a path computation. PCReq message includes a variety ofobjects that specify a set of constraints and attributes for the path tobe computed. PCEP may be extended to include a secure-node object. Thesecure-node object may be binary or may have multiple values fordifferent levels of security. The PCC node may use the secure-nodeobject in a PCReq message to request a secure path to PCE 140. PCE 140may discover information about secure nodes 120 from telemetry and/orrouting sources. For example, PCE 240 may discover secure nodeinformation from Interior Gateway Protocols (IGPs), Border GatewayProtocols (BGPs), BGP Link-State (BGP-LS), and the like.

One or more nodes 120 of network 110 may monitor the secure paths forfailures. Nodes 120 may use BFD authentication to monitor nodes 120 ofthe secure path. BFD single-hop authentication allows authentication forsingle-hop BFD sessions between two directly connected nodes 120. BFDsingle-hop authentication may use Message Digest 5 (MD5) and Secure HashAlgorithm 1 (SHA-1) authentication methods to provide security againstattacks on data links between a pair of directly connected nodesinvolved in a BFD session. BFD single-hop authentication may be appliedon data links between a BFD source-destination pair that communicatesthrough IPv4 and IPv6 protocols across a single IP hop that isassociated with an incoming interface. The communication may occurthrough tunnels, physical media, and/or virtual circuits.

In certain embodiments, single-hop BFD authentication may use a PCRvalue to detect failures in the secure path. PCR is a storage registerused to hold a PCR value that summarizes the measurement results thatare presented to the PCR. Detecting the failure in the secure path usingsingle-hop BFD authentication may include determining that a PCR valueincluded in a BFD packet is different than the expected PCR value. Forexample, when a BFD session is requested, the receiver of a BFD packetwill validate the incoming PCR value by querying another networkcomponent (e.g., a server or a controller). If the PCR value is notexpected, the BFD packet is dropped, and the BFD session will not becreated. The non-establishment of the BFD session prevents IGPs/BGPsfrom using this adjacency. If the incoming PCR value is valid, normalBFD processing of the BFD packet occurs.

Detecting the failure in the secure path using single-hop BFDauthentication may include determining that a PCR value included in aBFD packet has changed. For example, if at any time the incoming PCRvalue changes, the BFD session between nodes 120 of network 110terminates. The BFD clients (e.g., IGPs, BGPs, etc.) are notified, andthe network traffic is rerouted to an alternate secure path.Alternatively, the new PCR value may be validated by another networkcomponent (e.g., a server or a controller). For example, the PCR valuemay be determined to be valid change due to a software upgrade.

Controller 130 of system 100 is a component of network 110 thatdetermines the trustworthiness of one or more nodes 120 within network110. For example, controller 130 may determine that one or more nodes120 of network 110 are secure. As another example, controller 130 maydetermine that one or more nodes 120 of network 110 are insecure.Controller 130 may determine whether one or more nodes 120 of networkare secure by analyzing a security posture of each node 120, bydetermining a security level for each node and comparing the securitylevel to a threshold, and the like. Controller 130 may tag one or morenodes 120 of network 110 as secure and/or insecure. In certainembodiments, controller 130 pushes information associated with thesecurity of nodes 120 (e.g., which nodes are tagged secure/insecure) toone or more nodes 120 of network 110. In some embodiments, controller130 receives a request from one or more nodes 120 of network 110 for thesecurity information and, in response to receiving the request,communicates the security information to one or more nodes 120requesting the security information.

PCE 140 of system 100 is component (e.g., a router, a server, and thelike), application, or a node of network 110 that computes a networkpath or route and applies computational constraints. PCE 140 may computesecure paths through a plurality of nodes 120 of network 110 in responseto receiving a request from one or more nodes 120 (e.g., a PCC). PCE 140may calculate one or more secure paths using resource informationassociated with network 110 such as the topology of network 110,bandwidth, link costs, existing link state packets (LSPs), and the like.The network resource information may be stored in a traffic engineeringdatabase (TED). The network resource information may be discovered bypeering with IGPs, BGP-LS, and the like.

PCE 140 determines secure paths through network 110 using PCEP. Asmentioned above, PCEP may be extended to include a secure-node object.The PCC node may use the secure-node object in a PCReq message torequest a secure path to PCE 140. The secure-node object may be a PCEPattestation-token TLV. The format of the PCEP attestation token TLV mayinclude a TLV type that is to be assigned by IANA, a length of 2 to 252bytes, and a value that includes a 1-byte identifier (ID) to define theID of the token as a number ranging from 0 to 254 and 1 to 251 bytes ofbinary token data. The ID, which is the first byte of the value, may beused to distinguish different types of attestation tokens. A PCEPspeaker (e.g., PCE 140 or a PCC node) may indicate its support of theattestation token functionality by including one or moreattestation-token TLVs in the PCEP Open object. Upon establishing a PCEPsession, the PCEP speaker may verify its neighbor's support of theattestation tokens and validate if the neighbor is trustworthy. A PCEPspeaker may close the PCEP session to a neighbor that does not advertisea valid attestation token.

The attestation-token object-class and the attestation-token object-typemay be assigned by IANA. The attestation-token object-body may includeone or more attestation-token TLVs. The attestation-token object may beincluded within a PCEP message. When a PCEP speaker receives a PCEPmessage with an attestation-token object, the PCEP speaker may validateif the neighbor is trustworthy.

A PCC may monitor the status of PCE 140 (or of multiple PCEs) in a pathcomputation chain. A new attestation token flag (e.g., a bit) may beincluded in the monitoring object to monitor PCE 140 attestation tokens.The new attestation token flag in the monitoring object may be assignedby IANA. If the new attestation token flag of the monitoring object iscarried within the PCReq message or a Path Computation MonitoringRequest (PCMonReq) message, the attestation-token object must be presentwithin the corresponding PCReq message or PCMonReq message. The PCC mayuse the monitoring object to request PCE 140 (or multiple PCEs in a pathcomputation chain) to provide its attestation token. The PCC can thenvalidate if PCE 140 is trustworthy.

A PCE Discovery (PCED) TLV may be carried in an OSPF Router InformationLink State Advertisement (LSA) to facilitate PCE discovery using OSPF. Anew flag bit in the OSPF PCE capability flags may be used to indicatePCE attestation token support. A similar flag bit may be used forIntermediate System to Intermediate System (IS-IS) PCE discovery toallow IS-IS to indicate PCE attestation token support. This extensionmay be applied to the PCED information carried in BGP-LS. The new PCEattestation-token flag may be assigned by IANA in the PCE capabilityflags TLV. IF PCE 140 supports attestation token functionality, then thePCE attestation token capability flag is set. The discovering PCE maydecide to only use PCEs that support attestation token functionality.

A PCE-attestation-token sub-TLV may specify an attestation token thatmay be used by the discovering PCC to determine if the PCE has beencompromised. In certain embodiments, The PCE-attestation-token sub-TLVis included in the PCED sub-TLV carried within the IS-IS RouterInformation Capability TLV when the PCE-attestation-token support isset. In some embodiments, the PCE-attestation-token sub-TLV may beincluded in the PCED TLV carried within an OSPF Router Information LSAwhen the PCE-attestation-token support is set. The format of thePCE-attestation-token sub-TLV includes the following: a sub-TLV typeassigned by IANA (e.g., a 6 PCE-Attestation-Token), a length rangingfrom 2 to 252 bytes, and a value that includes a 1-byte ID to define theID of the token as a number ranging from 0 to 254 and 1 to 251 bytes ofbinary token data. The ID, which is the first byte of the value, may beused to distinguish different types of attestation tokens. Thediscovering PCC may use the PCE attestation token to determine if PCE140 is trustworthy prior to establishing a PCEP session to PCE 140.

One or more components (e.g., nodes 120, controller 130, and/or PCE 140)of network 110 may validate the secure paths of network 110. For securepaths that are calculated locally by one or more nodes 120 (e.g., aningress node), one or more nodes 120 may utilize controller 130 tovalidate the secure paths. For secure paths that are calculated remotelyby PCE 140, PCE 140 may validate the secure paths. If system 100 usesRSVP for signaling, the secure paths may be validated using the contentsof an RRO included in the RSVP message. The secure paths may bevalidated while network traffic is routed through the secure paths. Thesecure paths may be validated at predetermined time intervals.

In operation, an ingress node of system 100 determines a secure paththrough a first plurality of network nodes 120 within network 110. Theingress node also determines an alternate secure path through a secondplurality of network nodes 120 within network 110. The ingress node maycalculate the secure path locally using CSPF or determine the securepath remotely using information received from PCE 140. The ingress noderoutes incoming network traffic through the first plurality of nodes 120of the secure path. After the ingress node begins routing trafficthrough the secure path, the ingress node monitors the secure path forfailures using single-hop BFD authentication. If the ingress nodedetects a failure in the secure path, the ingress node reroutes thenetwork traffic through the second plurality of network nodes of thealternate secure path. As such, system 100 calculates secure networkpaths and quickly recovers from failures in the secure network paths,which may protect data that traverses network 110 from beingcompromised.

Although FIG. 1 illustrates a particular arrangement of network 110,nodes 120, controller 130, and PCE 140, this disclosure contemplates anysuitable arrangement of network 110, nodes 120, controller 130, and PCE140. For example, system 100 may not include controller 130 or PCE 140.As another example, PCE 140 may be external to network 110. AlthoughFIG. 1 illustrates a particular number of networks 110, nodes 120,controllers 130, and PCEs 140, this disclosure contemplates any suitablenumber of networks 110, nodes 120, controllers 130, and PCEs 140. Forexample, system 100 may include multiple PCEs 140.

FIG. 2 illustrates an example system 200 for securing network paths.System 200 or portions thereof may be associated with an entity, whichmay include any entity, such as a business or company (e.g., a serviceprovider) that calculates secure network paths and/or detects failuresin network paths. The components of system 200 may include any suitablecombination of hardware, firmware, and software. For example, thecomponents of system 200 may use one or more elements of the computersystem of FIG. 5 . System 200 includes network 110, nodes 120, PCE 140,secure path 210, and alternate secure path 220. Nodes 120 include PCC,N1, N2, N3, N4, N5, and N6. Network 110, nodes 120, and PCE 140 aredescribed in more detail above in FIG. 1 .

PCC of system 200 receives a request to route network traffic through asecure path of network 110 to destination node N3. PCC of network 110may receive this request from a network component that is external tonetwork 110. PCC communicates a PCReq message to PCE 140. The PCReqmessage includes a secure-node object that is used to request a securepath to PCE 140. The secure-node object may be a PCEP attestation token.PCC establishes a session with PCE 140 using PCEP. PCC may close thePCEP session if PCE 140 does not advertise a valid attestation token.

PCC requests a secure path and an alternate secure path from PCE 140.PCE 140 determines that nodes N1 through N6 of network 110 are secureusing information received from telemetry or routing sources (e.g.,IGPs, BGPs, and the like). PCE 140 calculates secure path 210 from PCCto N1, N1 to N2, and N2 to destination node N3. PCE 140 also calculatesalternate secure path 220 from PCC to N4, N4 to N5, N5 to N6, and N6 todestination node N3. PCE 140 communicates secure path 210 and alternatesecure path 220 to PCC.

PCC routes the network traffic through nodes N1, N2, and N3 of securepath 210. PCC monitors the secure path using BFD authentication. PCCmonitors secure path 210 for failures using single-hop BFDauthentication. For example, PCC may detect a failure in the secure pathby determining that a PCR value included in a BFD packet exchangedbetween two nodes (e.g., nodes N1 and N2) of the secure path haschanged. As another example, PCC may detect a failure in the secure pathby determining that a PCR value included in a BFD packet exchangedbetween two nodes (e.g., nodes N1 and N2) of the secure path isdifferent than an expected PCR value. If PCC detects a failure in thesecure path, PCC reroutes the network traffic though nodes N3, N5, N6,and N3 of alternate secure path 220. As such, system 200 calculatessecure network paths and quickly recovers from failures in the securenetwork paths, which may protect data that traverses network 110 viasecure paths from being compromised.

Although FIG. 2 illustrates PCC routing network traffic through securepath 210 and alternate secure path 220, this disclosure contemplates anysuitable component routing network traffic through secure path 210 andalternate secure path 220. For example, PCC of FIG. 2 may be replacedwith a local node that calculates secure path 210 and alternate securepath 220 locally using CSPF. Although FIG. 2 illustrates a particulararrangement of network 110, nodes 120, PCE 140, secure path 210, andalternate secure path 220, this disclosure contemplates any suitablearrangement of network 110, nodes 120, PCE 140, secure path 210, andalternate secure path 220. For example, PCE 140 may be external tonetwork 110. As another example, node N6 may be an insecure node, andalternate secure path 220 may bypass node N6. Although FIG. 2illustrates a particular number of networks 110, nodes 120, PCEs 140,secure paths 210, and alternate secure paths 220, this disclosurecontemplates any suitable number of networks 110, nodes 120, PCEs 140,secure paths 210, and alternate secure paths 220. For example, nodes 120may include more or less than seven nodes. As another example, PCE 140may calculate more than one alternate secure path.

FIG. 3 illustrates an example method 300 for calculating secure networkpaths within a network. Method 300 begins at step 310. At step 320, aningress node (e.g., node 120 of FIG. 1 ) of a network (e.g., network 110of FIG. 1 ) receives a request to route network traffic through thenetwork using a secure path. The ingress node may receive the requestfrom a node of a different network. Method 300 then moves from step 320to step 330, where the ingress node determines whether the secure pathwill be calculated locally or remotely. The ingress node may determineto calculate the secure path locally if the ingress node has informationon the security of the network elements. For example, the ingress nodemay calculate the secure path locally if the ingress node can determinewhich nodes of the network have been tagged as secure and/or insecure.If the ingress node cannot locally determine which nodes of the networkare secure, the secure path may be calculated remotely.

If, at step 330, the ingress node determines that the secure path willbe calculated locally, method 300 moves from step 330 to step 340. Atstep 340, the ingress node calculates, locally, a secure path through afirst plurality of network nodes using CSPF. CSPF may use a set ofconstraints to calculate the secure path, and the set of constraints mayinclude an additional constraint for verifying that the nodes of thesecure path are trustworthy. If, at step 330, the ingress nodedetermines that the secure path will be calculated remotely, method 300moves from step 330 to step 350. At step 350, a PCE (e.g., PCE 140 ofFIG. 1 ) calculates a secure path through a plurality of network nodesand communicates the path to the ingress node. Method 300 then movesfrom steps 340 and 350 to step 360. At step 360, the ingress node routestraffic through the plurality of network nodes of the secure path. Forexample, a tunnel (e.g., an RSVP tunnel) may be created along the securepath, and the ingress node may route traffic through the tunnel of thesecure path. Method 300 then moves from step 360 to step 370, wheremethod 300 ends.

Although this disclosure describes and illustrates particular steps ofmethod 300 of FIG. 3 as occurring in a particular order, this disclosurecontemplates any suitable steps of method 300 of FIG. 3 occurring in anysuitable order. For example, steps 340 and 350 directed to calculatingsecure paths may be performed before step 320 directed to receiving arequest to route the network traffic through a secure path. Althoughthis disclosure describes and illustrates an example method 300 forcalculating secure network paths including the particular steps of themethod of FIG. 3 , this disclosure contemplates any suitable method 300for calculating secure network paths, including any suitable steps,which may include all, some, or none of the steps of the method of FIG.3 , where appropriate. For example, method 300 may include additionalsteps directed to calculating one or more alternate secure paths throughthe network. Although this disclosure describes and illustratesparticular components, devices, or systems carrying out particular stepsof method 300 of FIG. 3 , this disclosure contemplates any suitablecombination of any suitable components, devices, or systems carrying outany suitable steps of method 300 of FIG. 3 .

FIG. 4 illustrates an example method 400 for detecting failures insecure network paths. Method 400 begins at step 410. At step 420, aningress node (e.g., node 120 of FIG. 1 ) of a network (e.g., network 110of FIG. 1 ) calculates, either locally or remotely, a secure paththrough a first plurality of network nodes. For example, the ingressnode may calculate the secure path locally using CSPF. CSPF may use aset of constraints to calculate the secure path, and the set ofconstraints may include a constraint associated with a determinationthat each node of the first plurality of nodes of the secure path istrustworthy. As another example, the ingress node may be a PCC node thatuses a PCE (e.g., PCE 140 of FIG. 1 ) to calculate the secure path.Method 400 then moves from step 420 to step 430.

At step 430, the ingress node of the network calculates, either locallyor remotely, an alternate secure path through a second plurality ofnetwork nodes. For example, the ingress node may calculate the alternatesecure path locally using CSPF. As another example, the ingress node maybe a PCC node that uses a PCE to calculate the alternate secure path.The ingress node may use the same process to calculate the secure pathand the alternate secure path. Method 400 then moves from step 430 tostep 440, where the ingress node routes network traffic through thefirst plurality of network nodes of the secure path. Method 400 thenmoves from step 440 to step 450.

At step 450, the ingress node determines a PCR value included in a BFDpacket received by a node of the first plurality of network nodes.Method 400 then moves from step 450 to step 460, where the ingress nodedetermines if a failure has been detected in the secure path usingsingle-hop BFD authentication. For example, a failure may be detected inthe secure path if the PCR value included in the BFD packet has changed.As another example, a failure may be detected in the secure path if thePCR value included in the BFD packet is different than an expected PCRvalue. If the ingress node determines that a failure has not beendetected in the secure path using single-hop BFD authentication, method400 moves from step 460 to step 480, where method 400 ends. If theingress node determines that a failure has been detected in the securepath using single-hop BFD authentication, method 400 moves from step 460to step 470, where the ingress node reroutes the network traffic throughthe second plurality of network nodes of the alternate secure path.Method 400 then moves from step 470 to step 480, where method 400 ends.

Although this disclosure describes and illustrates particular steps ofmethod 400 of FIG. 4 as occurring in a particular order, this disclosurecontemplates any suitable steps of method 400 of FIG. 4 occurring in anysuitable order. Moreover, although this disclosure describes andillustrates an example method 400 for detecting failures in securenetwork paths including the particular steps of the method of FIG. 4 ,this disclosure contemplates any suitable method 400 for detectingfailures in secure network paths, including any suitable steps, whichmay include all, some, or none of the steps of the method of FIG. 4 ,where appropriate. Furthermore, although this disclosure describes andillustrates particular components, devices, or systems carrying outparticular steps of the method of FIG. 4 , this disclosure contemplatesany suitable combination of any suitable components, devices, or systemscarrying out any suitable steps of the method of FIG. 4 .

FIG. 5 illustrates an example computer system 500. In particularembodiments, one or more computer systems 500 perform one or more stepsof one or more methods described or illustrated herein. In particularembodiments, one or more computer systems 500 provide functionalitydescribed or illustrated herein. In particular embodiments, softwarerunning on one or more computer systems 500 performs one or more stepsof one or more methods described or illustrated herein or providesfunctionality described or illustrated herein. Particular embodimentsinclude one or more portions of one or more computer systems 500.Herein, reference to a computer system may encompass a computing device,and vice versa, where appropriate. Moreover, reference to a computersystem may encompass one or more computer systems, where appropriate.

This disclosure contemplates any suitable number of computer systems500. This disclosure contemplates computer system 500 taking anysuitable physical form. As example and not by way of limitation,computer system 500 may be an embedded computer system, a system-on-chip(SOC), a single-board computer system (SBC) (such as, for example, acomputer-on-module (COM) or system-on-module (SOM)), a desktop computersystem, a laptop or notebook computer system, an interactive kiosk, amainframe, a mesh of computer systems, a mobile telephone, a personaldigital assistant (PDA), a server, a tablet computer system, anaugmented/virtual reality device, or a combination of two or more ofthese. Where appropriate, computer system 500 may include one or morecomputer systems 500; be unitary or distributed; span multiplelocations; span multiple machines; span multiple data centers; or residein a cloud, which may include one or more cloud components in one ormore networks. Where appropriate, one or more computer systems 500 mayperform without substantial spatial or temporal limitation one or moresteps of one or more methods described or illustrated herein. As anexample and not by way of limitation, one or more computer systems 500may perform in real time or in batch mode one or more steps of one ormore methods described or illustrated herein. One or more computersystems 500 may perform at different times or at different locations oneor more steps of one or more methods described or illustrated herein,where appropriate.

In particular embodiments, computer system 500 includes a processor 502,memory 504, storage 506, an input/output (I/O) interface 508, acommunication interface 510, and a bus 512. Although this disclosuredescribes and illustrates a particular computer system having aparticular number of particular components in a particular arrangement,this disclosure contemplates any suitable computer system having anysuitable number of any suitable components in any suitable arrangement.

In particular embodiments, processor 502 includes hardware for executinginstructions, such as those making up a computer program. As an exampleand not by way of limitation, to execute instructions, processor 502 mayretrieve (or fetch) the instructions from an internal register, aninternal cache, memory 504, or storage 506; decode and execute them; andthen write one or more results to an internal register, an internalcache, memory 504, or storage 506. In particular embodiments, processor502 may include one or more internal caches for data, instructions, oraddresses. This disclosure contemplates processor 502 including anysuitable number of any suitable internal caches, where appropriate. Asan example and not by way of limitation, processor 502 may include oneor more instruction caches, one or more data caches, and one or moretranslation lookaside buffers (TLBs). Instructions in the instructioncaches may be copies of instructions in memory 504 or storage 506, andthe instruction caches may speed up retrieval of those instructions byprocessor 502. Data in the data caches may be copies of data in memory504 or storage 506 for instructions executing at processor 502 tooperate on; the results of previous instructions executed at processor502 for access by subsequent instructions executing at processor 502 orfor writing to memory 504 or storage 506; or other suitable data. Thedata caches may speed up read or write operations by processor 502. TheTLBs may speed up virtual-address translation for processor 502. Inparticular embodiments, processor 502 may include one or more internalregisters for data, instructions, or addresses. This disclosurecontemplates processor 502 including any suitable number of any suitableinternal registers, where appropriate. Where appropriate, processor 502may include one or more arithmetic logic units (ALUs); be a multi-coreprocessor; or include one or more processors 502. Although thisdisclosure describes and illustrates a particular processor, thisdisclosure contemplates any suitable processor.

In particular embodiments, memory 504 includes main memory for storinginstructions for processor 502 to execute or data for processor 502 tooperate on. As an example and not by way of limitation, computer system500 may load instructions from storage 506 or another source (such as,for example, another computer system 500) to memory 504. Processor 502may then load the instructions from memory 504 to an internal registeror internal cache. To execute the instructions, processor 502 mayretrieve the instructions from the internal register or internal cacheand decode them. During or after execution of the instructions,processor 502 may write one or more results (which may be intermediateor final results) to the internal register or internal cache. Processor502 may then write one or more of those results to memory 504. Inparticular embodiments, processor 502 executes only instructions in oneor more internal registers or internal caches or in memory 504 (asopposed to storage 506 or elsewhere) and operates only on data in one ormore internal registers or internal caches or in memory 504 (as opposedto storage 506 or elsewhere). One or more memory buses (which may eachinclude an address bus and a data bus) may couple processor 502 tomemory 504. Bus 512 may include one or more memory buses, as describedbelow. In particular embodiments, one or more memory management units(MMUs) reside between processor 502 and memory 504 and facilitateaccesses to memory 504 requested by processor 502. In particularembodiments, memory 504 includes random access memory (RAM). This RAMmay be volatile memory, where appropriate. Where appropriate, this RAMmay be dynamic RAM (DRAM) or static RAM (SRAM). Moreover, whereappropriate, this RAM may be single-ported or multi-ported RAM. Thisdisclosure contemplates any suitable RAM. Memory 504 may include one ormore memories 504, where appropriate. Although this disclosure describesand illustrates particular memory, this disclosure contemplates anysuitable memory.

In particular embodiments, storage 506 includes mass storage for data orinstructions. As an example and not by way of limitation, storage 506may include a hard disk drive (HDD), a floppy disk drive, flash memory,an optical disc, a magneto-optical disc, magnetic tape, or a UniversalSerial Bus (USB) drive or a combination of two or more of these. Storage506 may include removable or non-removable (or fixed) media, whereappropriate. Storage 506 may be internal or external to computer system500, where appropriate. In particular embodiments, storage 506 isnon-volatile, solid-state memory. In particular embodiments, storage 506includes read-only memory (ROM). Where appropriate, this ROM may bemask-programmed ROM, programmable ROM (PROM), erasable PROM (EPROM),electrically erasable PROM (EEPROM), electrically alterable ROM (EAROM),or flash memory or a combination of two or more of these. Thisdisclosure contemplates mass storage 506 taking any suitable physicalform. Storage 506 may include one or more storage control unitsfacilitating communication between processor 502 and storage 506, whereappropriate. Where appropriate, storage 506 may include one or morestorages 506. Although this disclosure describes and illustratesparticular storage, this disclosure contemplates any suitable storage.

In particular embodiments, I/O interface 508 includes hardware,software, or both, providing one or more interfaces for communicationbetween computer system 500 and one or more I/O devices. Computer system500 may include one or more of these I/O devices, where appropriate. Oneor more of these I/O devices may enable communication between a personand computer system 500. As an example and not by way of limitation, anI/O device may include a keyboard, keypad, microphone, monitor, mouse,printer, scanner, speaker, still camera, stylus, tablet, touch screen,trackball, video camera, another suitable I/O device or a combination oftwo or more of these. An I/O device may include one or more sensors.This disclosure contemplates any suitable I/O devices and any suitableI/O interfaces 508 for them. Where appropriate, I/O interface 508 mayinclude one or more device or software drivers enabling processor 502 todrive one or more of these I/O devices. I/O interface 508 may includeone or more I/O interfaces 508, where appropriate. Although thisdisclosure describes and illustrates a particular I/O interface, thisdisclosure contemplates any suitable I/O interface.

In particular embodiments, communication interface 510 includeshardware, software, or both providing one or more interfaces forcommunication (such as, for example, packet-based communication) betweencomputer system 500 and one or more other computer systems 500 or one ormore networks. As an example and not by way of limitation, communicationinterface 510 may include a network interface controller (NIC) ornetwork adapter for communicating with an Ethernet or other wire-basednetwork or a wireless NIC (WNIC) or wireless adapter for communicatingwith a wireless network, such as a WI-FI network. This disclosurecontemplates any suitable network and any suitable communicationinterface 510 for it. As an example and not by way of limitation,computer system 500 may communicate with an ad hoc network, a personalarea network (PAN), a LAN, a WAN, a MAN, or one or more portions of theInternet or a combination of two or more of these. One or more portionsof one or more of these networks may be wired or wireless. As anexample, computer system 500 may communicate with a wireless PAN (WPAN)(such as, for example, a BLUETOOTH WPAN), a WI-FI network, a WI-MAXnetwork, a cellular telephone network (such as, for example, a GlobalSystem for Mobile Communications (GSM) network, a Long-Term Evolution(LTE) network, or a 5G network), or other suitable wireless network or acombination of two or more of these. Computer system 500 may include anysuitable communication interface 510 for any of these networks, whereappropriate. Communication interface 510 may include one or morecommunication interfaces 510, where appropriate. Although thisdisclosure describes and illustrates a particular communicationinterface, this disclosure contemplates any suitable communicationinterface.

In particular embodiments, bus 512 includes hardware, software, or bothcoupling components of computer system 500 to each other. As an exampleand not by way of limitation, bus 512 may include an AcceleratedGraphics Port (AGP) or other graphics bus, an Enhanced Industry StandardArchitecture (EISA) bus, a front-side bus (FSB), a HYPERTRANSPORT (HT)interconnect, an Industry Standard Architecture (ISA) bus, an INFINIBANDinterconnect, a low-pin-count (LPC) bus, a memory bus, a Micro ChannelArchitecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, aPCI-Express (PCIe) bus, a serial advanced technology attachment (SATA)bus, a Video Electronics Standards Association local (VLB) bus, oranother suitable bus or a combination of two or more of these. Bus 512may include one or more buses 512, where appropriate. Although thisdisclosure describes and illustrates a particular bus, this disclosurecontemplates any suitable bus or interconnect.

Herein, a computer-readable non-transitory storage medium or media mayinclude one or more semiconductor-based or other integrated circuits(ICs) (such, as for example, field-programmable gate arrays (FPGAs) orapplication-specific ICs (ASICs)), hard disk drives (HDDs), hybrid harddrives (HHDs), optical discs, optical disc drives (ODDs),magneto-optical discs, magneto-optical drives, floppy diskettes, floppydisk drives (FDDs), magnetic tapes, solid-state drives (SSDs),RAM-drives, SECURE DIGITAL cards or drives, any other suitablecomputer-readable non-transitory storage media, or any suitablecombination of two or more of these, where appropriate. Acomputer-readable non-transitory storage medium may be volatile,non-volatile, or a combination of volatile and non-volatile, whereappropriate.

Herein, “or” is inclusive and not exclusive, unless expressly indicatedotherwise or indicated otherwise by context. Therefore, herein, “A or B”means “A, B, or both,” unless expressly indicated otherwise or indicatedotherwise by context. Moreover, “and” is both joint and several, unlessexpressly indicated otherwise or indicated otherwise by context.Therefore, herein, “A and B” means “A and B, jointly or severally,”unless expressly indicated otherwise or indicated otherwise by context.

The scope of this disclosure encompasses all changes, substitutions,variations, alterations, and modifications to the example embodimentsdescribed or illustrated herein that a person having ordinary skill inthe art would comprehend. The scope of this disclosure is not limited tothe example embodiments described or illustrated herein. Moreover,although this disclosure describes and illustrates respectiveembodiments herein as including particular components, elements,feature, functions, operations, or steps, any of these embodiments mayinclude any combination or permutation of any of the components,elements, features, functions, operations, or steps described orillustrated anywhere herein that a person having ordinary skill in theart would comprehend. Furthermore, reference in the appended claims toan apparatus or system or a component of an apparatus or system beingadapted to, arranged to, capable of, configured to, enabled to, operableto, or operative to perform a particular function encompasses thatapparatus, system, component, whether or not it or that particularfunction is activated, turned on, or unlocked, as long as thatapparatus, system, or component is so adapted, arranged, capable,configured, enabled, operable, or operative. Additionally, although thisdisclosure describes or illustrates particular embodiments as providingparticular advantages, particular embodiments may provide none, some, orall of these advantages.

The embodiments disclosed herein are only examples, and the scope ofthis disclosure is not limited to them. Particular embodiments mayinclude all, some, or none of the components, elements, features,functions, operations, or steps of the embodiments disclosed herein.Embodiments according to the disclosure are in particular disclosed inthe attached claims directed to a method, a storage medium, a system anda computer program product, wherein any feature mentioned in one claimcategory, e.g. method, can be claimed in another claim category, e.g.system, as well. The dependencies or references back in the attachedclaims are chosen for formal reasons only. However, any subject matterresulting from a deliberate reference back to any previous claims (inparticular multiple dependencies) can be claimed as well, so that anycombination of claims and the features thereof are disclosed and can beclaimed regardless of the dependencies chosen in the attached claims.The subject-matter which can be claimed comprises not only thecombinations of features as set out in the attached claims but also anyother combination of features in the claims, wherein each featurementioned in the claims can be combined with any other feature orcombination of other features in the claims. Furthermore, any of theembodiments and features described or depicted herein can be claimed ina separate claim and/or in any combination with any embodiment orfeature described or depicted herein or with any of the features of theattached claims.

What is claimed is:
 1. An apparatus, comprising: one or more processors;and one or more computer-readable non-transitory storage media coupledto the one or more processors and comprising instructions that, whenexecuted by the one or more processors, cause the apparatus to performoperations comprising: determining a secure path through a firstplurality of network nodes within a network; determining an alternatesecure path through a second plurality of network nodes within thenetwork; routing network traffic through the first plurality of networknodes of the secure path; determining a Platform Configuration Register(PCR) value included in a Bidirectional Forwarding Detection (BFD)packet received by a node of the first plurality of network nodes;detecting a failure in the secure path using single-hop BFDauthentication; and rerouting the network traffic through the secondplurality of network nodes of the alternate secure path.
 2. Theapparatus of claim 1, wherein: the apparatus is a local device;determining the secure path through the first plurality of network nodeswithin the network comprises calculating, by the local device, thesecure path using constrained shortest path first (CSPF); CSPF uses aset of constraints to calculate the secure path through the firstplurality of network nodes within the network; and a constraint of theset of constraints is associated with a determination that each node ofthe first plurality of network nodes of the secure path is trustworthy.3. The apparatus of claim 1, wherein determining the secure path throughthe first plurality of network nodes within the network comprisesreceiving the secure path from a path computation element (PCE).
 4. Theapparatus of claim 1, the operations further comprising validating thesecure path through the first plurality of network nodes within thenetwork, wherein validating the secure path comprises one of thefollowing: receiving a validation of the secure path from a controllerof the network; receiving a validation of the secure path from a PCE ofthe network; or determining that the secure path is valid based oncontents received from a Record Route Object (RRO) of an ResourceReservation Protocol (RSVP) message.
 5. The apparatus of claim 1,wherein detecting the failure in the secure path using single-hop BFDauthentication comprises determining that the PCR value included in theBFD packet has changed.
 6. The apparatus of claim 1, wherein detectingthe failure in the secure path using single-hop BFD authenticationcomprises determining that the PCR value included in the BFD packet isdifferent than the expected PCR value.
 7. The apparatus of claim 1, theoperations further comprising communicating a path computation request(PCReq) message to a PCE to request a secure path to the PCE.
 8. Amethod, comprising: determining a secure path through a first pluralityof network nodes within a network; determining an alternate secure paththrough a second plurality of network nodes within the network; routingnetwork traffic through the first plurality of network nodes of thesecure path; determining a Platform Configuration Register (PCR) valueincluded in a Bidirectional Forwarding Detection (BFD) packet receivedby a node of the first plurality of network nodes; detecting a failurein the secure path using single-hop BFD authentication; and reroutingthe network traffic through the second plurality of network nodes of thealternate secure path.
 9. The method of claim 8, wherein: determiningthe secure path through the first plurality of network nodes within thenetwork comprises calculating, by a local device, the secure path usingconstrained shortest path first (CSPF); CSPF uses a set of constraintsto calculate the secure path through the first plurality of networknodes within the network; and a constraint of the set of constraints isassociated with a determination that each node of the first plurality ofnetwork nodes of the secure path is trustworthy.
 10. The method of claim8, wherein determining the secure path through the first plurality ofnetwork nodes within the network comprises receiving the secure pathfrom a path computation element (PCE).
 11. The method of claim 8,further comprising validating the secure path through the firstplurality of network nodes within the network, wherein validating thesecure path comprises one of the following: receiving a validation ofthe secure path from a controller of the network; receiving a validationof the secure path from a PCE of the network; or determining that thesecure path is valid based on contents received from a Record RouteObject (RRO) of an Resource Reservation Protocol (RSVP) message.
 12. Themethod of claim 8, wherein detecting the failure in the secure pathusing single-hop BFD authentication comprises determining that the PCRvalue included in the BFD packet has changed.
 13. The method of claim 8,wherein detecting the failure in the secure path using single-hop BFDauthentication comprises determining that the PCR value included in theBFD packet is different than the expected PCR value.
 14. The method ofclaim 8, further comprising communicating a path computation request(PCReq) message to a PCE to request a secure path to the PCE.
 15. One ormore computer-readable non-transitory storage media embodyinginstructions that, when executed by a processor, cause the processor toperform operations comprising: determining a secure path through a firstplurality of network nodes within a network; determining an alternatesecure path through a second plurality of network nodes within thenetwork; routing network traffic through the first plurality of networknodes of the secure path; determining a Platform Configuration Register(PCR) value included in a Bidirectional Forwarding Detection (BFD)packet received by a node of the first plurality of network nodes;detecting a failure in the secure path using single-hop BFDauthentication; and rerouting the network traffic through the secondplurality of network nodes of the alternate secure path.
 16. The one ormore computer-readable non-transitory storage media of claim 15,wherein: determining the secure path through the first plurality ofnetwork nodes within the network comprises calculating, by a localdevice, the secure path using constrained shortest path first (CSPF);CSPF uses a set of constraints to calculate the secure path through thefirst plurality of network nodes within the network; and a constraint ofthe set of constraints is associated with a determination that each nodeof the first plurality of network nodes of the secure path istrustworthy.
 17. The one or more computer-readable non-transitorystorage media of claim 15, wherein determining the secure path throughthe first plurality of network nodes within the network comprisesreceiving the secure path from a path computation element (PCE).
 18. Theone or more computer-readable non-transitory storage media of claim 15,the operations further comprising validating the secure path through thefirst plurality of network nodes within the network, wherein validatingthe secure path comprises one of the following: receiving a validationof the secure path from a controller of the network; receiving avalidation of the secure path from a PCE of the network; or determiningthat the secure path is valid based on contents received from a RecordRoute Object (RRO) of an Resource Reservation Protocol (RSVP) message.19. The one or more computer-readable non-transitory storage media ofclaim 15, wherein detecting the failure in the secure path usingsingle-hop BFD authentication comprises determining that the PCR valueincluded in the BFD packet has changed.
 20. The one or morecomputer-readable non-transitory storage media of claim 15, whereindetecting the failure in the secure path using single-hop BFDauthentication comprises determining that the PCR value included in theBFD packet is different than the expected PCR value.